Gemma Riley, 15, has made the final of the Teen Princess UK modelling contest

As she strikes a confident pose, it is easy to see why Gemma Riley is one of the contenders in a national modelling competition.

Yet it is only three months since the 15-year-old was in agony from a rare medical condition which contorted her spine into an S-shape.

Since then she has undergone a five-hour operation, during which surgeons clamped her spine in the right place with a titanium rod and pins.

Today, the only evidence of her ordeal is a 13-inch scar on her back which will fade in time – and the extra two inches she has gained in height following the operation.

It was during one of her first forays out after spending nearly two months recovering that talent scouts spotted Gemma at a fashion exhibition and persuaded her to enter the Miss Teen Princess UK competition for under-16s.

She was one of 20 girls who made it to the January finals and will discover next week if she is one of the three monthly winners who will go through to a live grand final in July.

‘I’ve finally got my life back on track,’ said the schoolgirl from Great Billing, Northamptonshire.

‘I had been in pain for years and it was making me depressed.

‘Since I can remember I’ve wanted to be a model but I gave up on it. Now I’ve had a massive boost of confidence and it couldn’t have come at a better time.’

Gemma had been suffering from back pain for some time when her mother began to notice her hunched way of walking.

She initially put it down to a teenage slouch but tests in February 2007 revealed the teenager had scoliosis.

The operation in October – which could have left her paralysed – was carried out at the John Radcliffe Hospital in Oxford.

Surgeons corrected the twist at the top of her spine by moving the vertebrae into position and pinning them in place.

They avoided interfering lower down as they feared she might be left unable to bend.

Gemma – who is now 5ft 8in – spent a week recovering in hospital and a further six weeks at home before going back to school part-time.

Shortly before Christmas she was at the Clothes Show Live exhibition in Birmingham when talent scouts urged her to enter the competition.

Her mother Selma, 42, who has two other daughters and a son, admitted it had taken her more than a year to realise something was wrong.

‘I’d noticed Gemma was really hunched up and walking funny but I thought she was being a typical teenager and slouching,’ she said.

‘I feel bad that I didn’t notice anything sooner but she was shy about her body and always hid it away. She was aware something wasn’t right and was embarrassed by it.'